Hi all,
I have a little problem. I am implementing an application that uses the
OpenLDAP libraries. Until not too much time ago, linking with OpenSSL was
sufficiently safe (on almost every Linux distros) and providing my own
verification function through the SSL_CTX (by using the ldap_set_option(m_ldap,
LDAP_OPT_SERVER_CERTIFICATE, _my_verify)) was easy.
Now, Linux distros started to use GnuTLS, NSS, and OpenSSL as the crypto
API.
My question is: how do I develop an application that when deployed on different
systems might need to use functions and data structures from different crypto-api
(e.g., when I distribute the binaries of my app) ?
How can I retrieve that info *at runtime* (I'd like my binaries to be compatible) ?

At least, is there a function that allows me to know which crypto APIs are
expected by libldap_r (so that I don't pass in the wrong data structure
since it is a (void *)) ? Or at least, is there a way to set/get options so that
I would know which API is in use ?

Good question. The implementation name is present in the library but there is
no option to retrieve it. Unfortunately it was deleted from the earlier
version of the new TLS code (which allowed the TLS implementation to be
dynamically selected at runtime). I've added the option back to the git
master, but it's a bit late to help your immediate problem.